The objective of this study is to show historical characters of the Mitsui-gumi House at Kaiun-bashi that mixed the European style with the Japanese style in the early Meiji Era. The early Meiji Era was times when Japanese encountered European civilization and advanced European technology. A summary will be given as follows; 1) The House was built in 1872 as a social status symbol of the Mitsui-gumi. 2) The House had mixed styles : one copying the European style and another copying the Japanese style of the feudal times. 3) The owner meant to use the European style for the House, which would bring prosperity to him. 4) The owner used positively the Yatsumune-Zukuri for the roof of the House that was an element of Japanese castles in the feudal times.